Various types of environmentally friendly vehicles, such as electric and hybrid electric vehicles are being developed. Since an electric vehicle is driven using charging/discharging energy of a battery pack, the electric vehicle has been well received by consumers due to improved fuel efficiency and reduction in pollutants emitted from the vehicle compared to an engine-driven vehicle. Thus, a battery, which is a core part of the electric vehicle, is often the subject of interest and study. Particularly, various studies have been performed regarding construction of charging infrastructures for batteries for environmentally friendly vehicles.
Electric vehicle supply equipment (EVSE) connected to a distribution system is typically used to charge a battery for an electric vehicle. Charging interface components such as a charging connector (not shown) and an inlet (not shown) are provided between the EVSE and the electric vehicle. A control pilot signal is generated by the EVSE and is transmitted to the electric vehicle via a charging coupler and a contact. Maximum output of the EVSE is limited when the electric vehicle is slowly charged. When the electric vehicle is charged in excess of the limited output, a charging interruption phenomenon may occur. In particular, the same phenomenon may occur when charging is attempted after a first interruption. For example, when the EVSE is charged by a charging current that exceeds a control pilot (CP) duty (%) of a charger at the beginning of charging, no charging of the battery occurs. Therefore charging is forcibly ended by a fail-safe device for safety reasons when the EVSE uses a current greater than the CP duty (%).